Thanks Peter. I read that a few times, and then 3 more times after you told me too before it registered. DUH!

woudln't another example of twin turbo (bi turbo) 4 cylinder be the last generation Audi S4?

the current ones are v6 twin turbos, and the older ones are a striaght 5 with a single turbo, 5/2 is audi math they could make it divided

mike

Back from the dead I know.....

So, from engine flange to turbo flange runner lenght should be 16-18 inches long....longer the better but equal lenght. From engine flange to WG Flange, 10-15 inches long equal lenght..... am i right in this assumption?

Thanks

G

^^bump..... anyone care to comment on the resume fot the runner lenght?

Bump ^^ I need to know also.
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O

Making the runners from the engine to the turbo around 16-18 inches long, with the assumption of, the longer the better, is correct. On a manifold with equal length runners, this will allow the turbine to experience equal exhaust pulses from each rotor, with equal timing/frequency. This will in turn result in faster spool up, taking advantage of the split turbine housing.

As for the WG runners, keeping them of equal length, and therefore equal volume is also important. When using a single WG to control boost there will be collector, where the runners will merge together before passing through the WG itself. It is the volume/length of the runners from the engine, to the collector, that is of importance. Basically, the WG collector, is the only point where the exhaust pulse from rotor 1 and 2 get to interact with eachother. The longer the path that any resonance/harmonic waves, caused by the interaction of the pulses, must travel, the less effect they will have on the following exhaust events.

So in summary, make the WG runners as long as possible too, while being sure to make them of equal length/volume, at the same time.